Friday, November 14, 2008

Conspicuous Correlation: Retail Sales October 2008

Today, the U.S. Census Bureau released its latest nominal read of retail sales showing a decline of 2.8% from September 2008 and 4.1% decline from October 2007 on an aggregate of all items including food, fuel and healthcare services.

Discretionary retail sales including home furnishings, home garden and building materials, consumer electronics and department store sales also experienced another significant decline falling 4.57% compared to October 2007.

Further, adjusted for inflation, “real” discretionary retail sales declined 8.83% since October 2007.

On a “nominal” basis, there appeared to be “rough correlation” between strong home value appreciation and strong retail spending preceding the housing bust and an even stronger correlation when home values started to decline.

The following charts show my initial analysis plotting the year-over-year change to an aggregate series consisting of the primary discretionary retail sales categories that I termed the “discretionary” retail sales series and the year-over-year change to the S&P/Case-Shiller Composite home price index since 1993 and since 2000.

As you can see there was, at the very least, a coincidental change to home values and consumer spending during the boom and then the bust, but as home values have continued to decline, retail spending has remained low but has not continued to consistently contract.

One problem with this initial analysis is that both retail sales and the S&P/Case-Shiller Composite index are reported in “nominal” (i.e. non-inflation adjusted) terms and thus result in a somewhat skewed view especially for the retail sales data.

As you can see from the above charts (click for larger version), adjusted for inflation (CPI for retail sales, CPI “less shelter” for S&P/Case-Shiller Composite) the “rough correlation” between the year-over-year change to the “discretionary” retail sales series and the year-over-year S&P/Case-Shiller Composite series seems now even more significant.